This invention relates to poly(arylene sulfide). In one of its aspects this invention relates to preparing shaped objects of poly(arylene sulfide). In still another aspect of this invention it relates to shaped object prepared from poly(arylene sulfide). In still another aspect of the invention it relates to the pultrusion of fiber strands impregnated with poly(arylene sulfide). In still another aspect of the invention it relates to processing steps useful in the pultrusion of fiber strands impregnated with poly(arylene sulfide). In yet another aspect of the invention it relates to molded objects produced using the processes described.
The production of molded products of polyester resin matrix reinforced with glass fiber by the pultrusion process is well established. In this process, a glass fiber roving is pulled from a creel, passed through a polyester resin bath for impregnation of the roving with the resin and with precise control for uniformity the excess resin is squeezed off the roving while passing through a preformer with a final shaping and curing in a heated die. The pulling mechanism located in the process after the curing die causes the roving to be forwarded through the processing system and then to further processing such as being cut to a desired length. Although the vast majority of pultruded products are formed from polyester resins reinforced with glass fibers, other fibers such as carbon, aramid and hydrid fibers which involve more than one type of fiber have also been used as reinforcement and such resins as vinyl ester and epoxy have seen use as the matrix material. Until recently, the use of thermoplastic resins in the pultrusion process has been almost non-existent. In the present invention, is set forth a method for producing pultruded products using poly(arylene sulfide) as the matrix material.
As will be noted below, pultrusion of poly(arylene sulfide) requires novel adjustment of processing techniques--including fiber content of pultrusion prepreg, size of polymer particle for impregnation, pulling tension, and die configuration--as compared to the known processes using thermosetting epoxy and polyester resins normally used in pultrusion processes.
Using poly(arylene sulfide) as the matrix provides pultruded products that have advantages over the same products made from other materials such as steel, wood, or aluminum. The pultruded products are lightweight, can be designed for the strength and stiffness required, are non-rusting, are corrosion resistant to numerous chemicals and gases, are non-conductive, and have low thermal conductivity. The products have potential use both as parts that become a portion of a larger fabricated structure when the pultrusion is incorporated into the overall fabrication (frames, supports, gratings) and in the type of products which are themselves structures (ladders, walkways, guardrails).
It is therefore an object of this invention to provide a method for preparing shaped objects of reinforced plastic in which poly(arylene sulfide) is the matrix for strands of reinforcing material. It is another object of this invention to provide a method for pultruding fiber strands impregnated with poly(arylene sulfide). It is still another object of this invention to provide shaped objects having poly(arylene sulfide) matrix and fiber strand reinforcement. It is still another object of this invention to provide pultruded objects in which fiber strand reinforcement is surrounded with a poly(arylene sulfide) matrix.
Other aspects, objects and the various advantages of this invention will become apparent upon the study of the specification of this application along with the drawing and the appended claims.